The invention related to an apparatus for the conversion of pollutants contained in effluents and effluent sludges, in particular of harmful substances and more particularly of excreta, into harmless substances, comprising one or more revolving hollow bodies accommodated in conversion pools or sludge aerating pools adapted to be raised completely from the water on one side of the conversion or sludge aerating pool and to be totally immersed on the other side, that portion thereof which is uppermost on the emerging side being lowermost on the immersion side and vice versa.
Apparatus comprising hollow bodies of the aforesaid type, the walls of which comprise a large number of perforations, and the perforations being confined to that wall region which is uppermost on the emerging side are employed in practice. In such apparatus there exists a risk that the sludge which has entered the hollow bodies on their way underneath the water surface or which is contained in the water which has thus entered, fails to drain completely or at all from the hollow bodies on their way above the water surface or to be resuspended during the dipping of the hollow body into the water on the immersion side, thus resulting in persistent sludge deposits in the hollow bodies. In these permanent sludge deposits in the hollow bodies there may then take place anaerobic fermentation resulting in rotting of the pollutants but without their complete decomposition.